Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Group 4 metals (Titanium, Zirconium, Hafnium) are crucial in catalysis.
• Pyrrole-based ligands offer unique electronic and steric properties.
• Phosphine ligands are versatile in stabilizing metal centers.

Purpose of the Study:

• To synthesize and characterize novel group 4 metal complexes.
• To investigate the reactivity of these complexes with various reagents.
• To explore the structural diversity and potential applications of these new compounds.

Main Methods:

• Synthesis of group 4 metal complexes using [P(NH)P-iPr] ligand.
• Reactions with metal halides, cyclopentadienyl sodium, and alkyl halides.
• Characterization using NMR spectroscopy and X-ray crystallography.
• Density Functional Theory (DFT) calculations for structural analysis.

Main Results:

• Formation of dimeric and mononuclear complexes with Zr and Hf.
• Synthesis of trialkyl and amido complexes with Ti, Zr, and Hf.
• Identification of a κ1N-bound PNP ligand as the most stable species in Ti complexes.
• Isolation of anionic seven-coordinate tetrabromo complexes of Zr and Hf.

Conclusions:

• The pyrrole-phosphine ligand enables the synthesis of diverse group 4 metal complexes.
• The reactivity of these complexes can be tuned by varying metal precursors and reaction conditions.
• Structural and electronic properties were elucidated through spectroscopic and crystallographic methods.